The Influence of Complex Terrain on the Turin, New York Tornado of 2023

Although uncommon as compared to other regions of the United States, the Northeast does experience significant tornados; those rated F/EF3 and above, of which some have had profound impacts on the region. Due to the diverse topography of the region, including its many northsouth oriented river valleys, most of these significant tornados traversed considerable changes in elevation throughout their lifetime. This study seeks to better understand the impacts of local topography on the intensity and overall progression of a significant tornadic event through using the most recent Northeast EF3: the Turin, NY tornado. With the consideration of previous studies involving the effects of terrain on tornados, we broke terrains effects into two factors: valley channeling, where a valley favorably oriented can forced a backed surface flow and increase low-level shear, producing an environment better capable of severe hazards in said valley, as well as vortex stretching, where descent/ascent of terrain such as off a hill causes stretching and spin up of the vortex or vice versa. A synoptic and mesoscale overview of the event was carried out first, finding a low-end tornadic environment. Model simulations of the Turin supercell were carried out using the Weather and Research Forecasting (WRF) model to test the effects of various terrain configurations on the strength and progression of the storm, providing an in-depth analysis of both the valley channeling and vortex stretching effects previously mentioned. It was found the combination of both effects was responsible for the significant intensity of the Turin tornado, as the storm was noticeably weaker in the absence of these effects. Additionally, it was found these effects play a secondary role to storm-scale effects such as storm splitting, mergers, and nudges in alteration of the mesocyclonic vortex. Links were drawn to other noteworthy past events, providing confidence in our findings. Keywords: Significant tornado, effects of topography, Northeast US tornado